Edge-emitting light-emitting device having improved external luminous efficiency and self-scanning light-emitting device array comprising the same

ABSTRACT

A self-scanning light-emitting element array using an end face light-emitting thyristor having improved external emission efficiency is provided. To improve the external emission efficiency of the end face light-emitting thyristor, the present invention adopts such structure that the current injected from an anode is concentrated to near the end face of the light-emitting thyristor. A self-scanning light-emitting element array is implemented by using such end face light-emitting thyristor.

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/043,106, filed Sep. 24, 1996, now U.S. Pat. No. 6,180,960,issued Jan. 30, 2001.

TECHNICAL FIELD

The present invention generally relates to an end face light-emittingelement having an increased light emission efficiency and aself-scanning light-emitting element array using such end facelight-emitting elements, particularly to a three-terminal end facelight-emitting thyristor and a self-scanning light-emitting elementarray using such three-terminal end face light-emitting thyristors.

BACKGROUND ART

An end face light-emitting diode array has heretofore been known as ahigh-density light-emitting element array which may increase a couplingefficiency to lenses. The basic structure of such end facelight-emitting diode arrays is described in “IEEE Trans. ElectronDevices, ED-26, 1230 (1979)”, for example. Conventional end facelight-emitting diode arrays, however, have problems such that there aredifficulties in fabricating them high-density, compact and low-cost,because each of diodes is to be connected to a driving circuit in orderto drive the end face light-emitting diode array.

To resolve these problems, the present applicant has already disclosed aself-scanning end face light-emitting element array having a pnpnstructure in which a driving circuit and a light-emitting element arrayare integrated in one chip (see Japanese Patent Publication No.9-85985). A three-terminal end face light-emitting thyristor which isused as the end face light-emitting element disclosed in thispublication is shown in FIGS. 1A and 1B. FIG. 1A shows plan view andFIG. 1B cross-sectional view taken along the X-Y line in FIG. 1A.

The end face light-emitting thyristor comprises an n-type semiconductorlayer 12, a p-type semiconductor layer 14, an n-type semiconductor layer16, and a p-type semiconductor layer 18 formed on an n-typesemiconductor substrate 10; an anode electrode 20 formed on the p-typesemiconductor 18 so as to make ohmic contact therewith; and a gateelectrode 22 formed on the n-type semiconductor layer 16 so as to makeohmic contact therewith. On the entire structure provided is aninsulting film (not shown) made of a light-transmitting, insulatingmaterial, on which an Al wiring 24 is further provided (see FIG. 1A).The Al wiring 24 is not shown in FIG. 1B for simplifying the figure. Inthe insulating film opened is a contact hole 26 for electricallyconnecting the anode electrode 20 to the Al wiring 26. While not shownin FIG. 1B, a cathode electrode is provided on the bottom surface of thesubstrate 10.

In this conventional end face light-emitting thyristor, light is emittedfrom an end face 23 of the semiconductor layers 14, 16 both thereofconstitute gate layers. As shown by arrows in FIG. 1B, the most ofcurrent fed from the anode electrode 20 flows directly downward (thisinjected current is indicated by I1), and a part of the current flowsgoing round to the gate electrode 22 (this injected current is indicatedby I2). Although both of these injected current I1 and I2 contribute tolight generation in the semiconductor layers, the light generated by thecurrent I2 cannot contribute to external light emission from the endface 23 since the current I2 generates light in the area apart from theend face 23. As a result, the amount of light emitted from the end faceis reduced only by the amount of light not contributed, thus externallight emission efficiency is decreased.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an end facelight-emitting thyristor having improved external light emissionefficiency.

Another object of the present invention is to provide a self-scanninglight-emitting element array using such end face light-emittingthyristor.

According to a first aspect of the present invention, an end facelight-emitting thyristor for emitting light from an end face thereofcomprises a first semiconductor layer of a first conductivity type, asecond semiconductor layer of a second conductivity type, a thirdsemiconductor layer of the first conductivity type, and a fourthsemiconductor layer of the second conductivity type stacked in thatorder on a substrate of the first conductivity type; an electrodeprovided in such a manner that a part thereof makes ohmic contact withthe fourth semiconductor layer in the vicinity of the end face forinjecting current into the semiconductor layers; and an insulating layerprovided between the fourth semiconductor layer and the part of theelectrode that is not made ohmic contact with the fourth semiconductorlayer.

It is also possible that an opening is formed in the part of theinsulating layer faced to the end face, making the electrode ohmiccontact with the fourth semiconductor layer via the opening.

In this way, the flow of the current injected from the electrode isconcentrated to near the end face of the light-emitting thyristor.

According to a second aspect of the present invention, an end facelight-emitting thyristor for emitting light from an end face thereofcomprises a first semiconductor layer of a first conductivity type, asecond semiconductor layer of a second conductivity type, a thirdsemiconductor layer of the first conductivity type, and a fourthsemiconductor layer of the second conductivity type stacked in thatorder on a substrate of the first conductivity type; a first electrodeprovided on the fourth semiconductor layer; and a second electrodeprovided on the third semiconductor layer. The first, second and thirdsemiconductor layers have a necked portion or a groove between a regionincluding the first electrode and a region including the secondelectrode.

By providing such necked portion or groove, the resistance value betweenthe region including the first electrode and the region including thesecond electrode becomes larger. As a result, the external emissionefficiency is increased because the current component which flows towardthe region including the second electrode is decreased, thus the most ofthe injected current flows in the region including the first electrode.

Using end face light-emitting thyristor described above, a self-scanninglight-emitting element array of the following structure may beimplemented.

A first structure of the self-scanning light-emitting element arraycomprises a plurality of light-emitting elements each having a controlelectrode for controlling threshold voltage or current forlight-emitting operation. The control electrodes of the light-emittingelements are connected to the control electrode of at least onelight-emitting element located in the vicinity thereof via aninteractive resistor or an electrically unidirectional element, and aplurality of wiring to which voltage or current is applied are connectedto electrodes for controlling the light emission of light-emittingelements.

A second structure of the self-scanning light-emitting element arraycomprises a self-scanning transfer element array having such a structurethat a plurality of transfer elements each having a control electrodefor controlling threshold voltage or current for transfer operation arearranged, the control electrodes of the transfer elements are connectedto the control electrode of at least one transfer element located in thevicinity thereof via an interactive resistor or an electricallyunidirectional element, power-supply lines are connected to the transferelements by electrical means, and clock lines are connected to thetransfer elements; and a light-emitting element array having such astructure that a plurality of light-emitting elements each having acontrol electrode for controlling threshold voltage or current arearranged, the control electrodes of the light-emitting element array areconnected to the control electrodes of said transfer elements byelectrical means, and lines for applying current for light emission ofthe light-emitting element are provided.

According to the structures described above, increased external emissionefficiency, high-densitiy, compact and low-cost self-scanninglight-emitting element arrays may be implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating the structure of aconventional end face light-emitting thyristor.

FIGS. 2A and 2B are diagrams illustrating the structure of an end facelight-emitting thyristor in a first embodiment of the present invention.

FIGS. 3A and 3B are diagrams illustrating the structure of an end facelight-emitting thyristor in a second embodiment of the presentinvention.

FIGS. 4A and 4B are diagrams illustrating the structure of an end facelight-emitting thyristor in a third embodiment of the present invention.

FIGS. 5A and 5B are diagrams illustrating the structure of an end facelight-emitting thyristor in a fourth embodiment of the presentinvention.

FIG. 6 is an equivalent circuit diagram of a first structure of aself-scanning light-emitting element array.

FIG. 7 is an equivalent circuit diagram of a second structure of aself-scanning light-emitting element array.

FIG. 8 is an equivalent circuit diagram of a third structure of aself-scanning light-emitting element array.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of an end face light-emitting thyristor according tothe present invention will now be described. FIG. 2A is a plan view ofan end face light-emitting thyristor of the first embodiment, and FIG.2B is a cross-sectional view taken along the X-Y line in FIG. 2A. Inthis end face light-emitting thyristor, an n-type semiconductor layer (acathode layer) 12, a p-type semiconductor (a base layer) 14, an n-typesemiconductor layer (a base layer) 16, and a p-type semiconductor layer(an anode layer) 18 are stacked on an n-type semiconductor substrate 10.On the anode layer 18 provided is an insulting film 19 apart from theend face 23. On the insulating film 19 and the part of the anode layer18 not covered by the insulating film 19 provided is an anode electrode20. On the gate layer 16 provided is a gate electrode 22.

The end face light-emitting thyristor of this embodiment is differentfrom the conventional thyristor shown in FIGS. 1A and 1B only in thatthe insulating film 19 is further provided on the anode layer 18. Thereason why the insulating film 19 is provided will be explained in thefollowing. In order to increase the external emission efficiency of anend face light-emitting thyristor, it is required that the anodeelectrode 20 is to be ohmic contacted with the anode layer 18 in thevicinity of the end face 23 so that the flow of the current injectedfrom the anode electrode 20 is concentrated to near the end face 23. Thesize of the anode electrode 20 itself cannot be made small toconcentrate the current to near the end face 23, since the anodeelectrode is required to make contact with the Al wiring as shown inFIG. 1A. In this embodiment, consequently, between the anode 20 and theanode layer 18 provided is the insulating film 19 apart from the endface 23 so as to remain the region where the anode electrode 20 is ohmiccontacted to the anode layer 18 only in the vicinity of the end face 23.In this case, if the contact area between the anode electrode 20 and theanode layer 18 becomes smaller, then the flow distribution of thecurrent injected from the anode electrode 20 is narrowed so that theexternal emission efficiency is increased. Assuming that the length andwidth of the contact area between the anode electrode 20 and the anodelayer 18 are L and W, respectively, as shown in FIG. 2A, when the case 1in which L=5 μm and W=10 μm and the case 2 in which L=10 μm and W=10 μmare compared with each other, it is appreciated that the case 1 havingsmaller L realizes about 50% larger amount of light emission than thatof the case 2.

A second embodiment of an end face light-emitting thyristor according tothe present invention will now be described. FIG. 3A is a plan view ofan end face light-emitting thyristor of the second embodiment, and FIG.3B is a cross-sectional view taken along the X-Y line in FIG. 3A. It isnoted that elements similar to those in FIGS. 2A and 2B are designatedby the same reference numeral as in FIGS. 2A and 2B.

The second embodiment intends to narrow the current flow distribution ina width direction of the anode electrode in the first embodiment. Forthat purpose, an insulating film 30 is provided on the anode layer 18starting from the end face 23, and an opening (the width W₀, and thelength L₀) 32 is formed in the insulating film at the end face 23.Through the opening 32, made is a part of the anode electrode 20 ohmiccontact with the anode layer 18. It is possible, therefore, to selectthe contact area (W₀×L₀) of the anode electrode 20 to the anode layer18. According to this structure, the width W₀ of the opening 32 may besmaller than the width W of the electrode 20, resulting in thesubstantial decrease of the contact area of the anode electrode 20 tothe anode layer 18. Therefore, the density of the current through thesemiconductor layers is increased so that the external emissionefficiency may be elevated.

A third embodiment of an end face light-emitting thyristor according tothe present invention will now be described. FIGS. 4A and 4B are planand side views of an end face light-emitting thyristor according to thethird embodiment. The structure of this embodiment is essentially thesame as that of the thyristor shown in FIGS. 1A and 1B. In FIGS. 4A and4B, therefore, elements similar to those in FIGS. 1A and 1B aredesignated by the same reference numeral as in FIGS. 1A and 1B.

In the end face light-emitting thyristor of this embodiment, notches 28are provided on both sides of the semiconductor layers 12, 14 and 16between the region 25 including the anode electrode 20 and the region 27including the gate electrode 22 to form a necked portion 30 on thesemiconductor layer 12, 14 and 16. The notches 28 can be easily formedby etching.

Since the width d of the necked portion 30 is smaller than the width Dof the semiconductor layer 12, 14 and 16, the resistance value of thenecked portion 30 becomes larger. As a result, the current injected fromthe anode electrode 20 does not flow toward the gate electrode as shownby an arrow in FIG. 4B, thus contributing more to light generation underthe anode electrode. When D=13 μm, and d=5 μm, the external emissionefficiency is increased by about 10%.

In order to increase further the external emission efficiency of the endface light-emitting thyristor, the contact area between the anodeelectrode 20 and the anode layer 18 is to be decreased as shown in thefirst and second embodiments.

A fourth embodiment of an end face light-emitting thyristor according tothe present invention will now be described. FIGS. 5A and 5B are planand side views of an end face light-emitting thyristor according to thefourth embodiment. The structure of this embodiment is essentially thesame as that of the thyristor shown in FIGS. 1A and 1B. In FIGS. 5A and5B, therefore, elements similar to those in FIGS. 1A and 1B aredesignated by the same reference numeral as in FIGS. 1A and 1B.

According to the end face light-emitting thyristor of this embodiment, agroove 32 is provided on the n-type semiconductor (n-type gate layer)between the region 25 including the anode electrode 20 and the region 27including the gate electrode 22. The depth t of the groove 32 is suchthat the groove is kept a certain distance away from a depletion layerformed between the n-type semiconductor layer 16 and the p-typesemiconductor layer 14. This is because if the groove 32 reaches thedepletion layer, the resistance value of the n-type semiconductor layer16 between the anode electrode 20 and the gate electrode 22 becomeslarge, remarkably aggravating the electrical property of the thyristor.

By providing the groove 32, the resistance value between the anodeelectrode region and the gate electrode becomes large. As a result, thecurrent injected from the anode electrode 20 does not flow toward thegate electrode as shown by an arrow in FIG. 5B, thus contributing tolight generation under the anode electrode. When the thickness T of then-type semiconductor layer 16 is 1 μm and the depth t of the groove is0.5 μm, the external emission efficiency is increased by about 10%.

In order to increase further the external emission efficiency of the endface light-emitting thyristor, the contact area between the anodeelectrode 20 and the anode layer 18 is to be decreased as shown in thefirst and second embodiments.

In embodiments 1, 2, 3 and 4 described above, semiconductor layers arestacked in the order of npnp on an n-type semiconductor substrate.Needless to say, this invention can be applied to a structure wheresemiconductor layers are stacked in the order of pnpn on a p-typesemiconductor substrate. In this case, the type of electrode provided onthe uppermost n-type semiconductor layer is a cathode electrode, whilethat provided on the rear surface of the p-type semiconductor substrateis an anode electrode.

The reason why a semiconductor layer of the same conductivity type asthe semiconductor substrate is stacked immediately above thesemiconductor substrate in the above embodiments is in the following. Ingeneral, when a pn (or np) junction is formed directly on the surface ofa semiconductor substrate, the poor crystallinity of the formedsemiconductor layer tends to degrade the properties of a device. This isbecause when a crystal layer is epitaxially grown on a substratesurface, the crystallinity near the substrate is degraded compared withthe crystallinity after the crystal layer has been grown above a certainlevel. The above problem can be solved by first forming the samesemiconductor layer as the semiconductor substrate, and then forming thepn (or np) junction. It is therefore desirable to interpose thesemiconductor layer therebetween.

Three fundamental structures of self-scanning light-emitting elementarrays to which the end face light-emitting thyristor of the presentinvention can be applied will now be described.

FIG. 6 shows an equivalent circuit diagram of a first fundamentalstructure of the self-scanning light-emitting element array. Accordingto the structure, end face light-emitting thyristors . . . T⁻², T⁻¹, T₀,T₊₁, T₊₂, . . . are used as light-emitting elements, each of thyristorscomprising gate electrodes . . . G⁻², G⁻¹, G₀, G₊₁, G₊₂ . . . ,respectively. Supply voltage V_(GK) is applied to all of the gateelectrodes via a load resistor R_(L), respectively. The neighboring gateelectrodes are electrically connected to each other via a resistor R_(I)to obtain interaction. Each of three transfer clock (φ₁, φ₂, φ₃) linesis connected to the anode electrode of each light-emitting element atintervals of three elements (in a repeated manner).

The operation of this self-scanning light-emitting element array willnow be described. Assume that the transfer clock φ₃ is at a high level,and the light-emitting thyristor T₀ is turned on. At this time, thevoltage of the gate electrode G₀ is lowered to a level near zero voltsdue to the characteristic of the light-emitting thyristor. Assuming thatthe supply voltage V_(GK) is 5 volts, the gate voltage of eachlight-emitting thyristor is determined by the resistor networkconsisting of the load resistors R_(L) and the interactive resistorsR_(I). The gate voltage of a thyristor near the light-emitting thyristorT₀ is lowered most, and the gate voltage V(G) of each subsequentthyristor rises as it is remote from the thyristor T₀. This can beexpressed as follows:

V(G ₀)<V(G ₊₁)=V(G ⁻¹)<V(G ₊₂)=V(G ⁻²)  (1)

The difference among these voltages can be set by properly selecting thevalues of the load resistor R_(L) and the interactive resistor R_(I).

It is known that the turn-on voltage V_(ON) of the light-emittingthyristor is a voltage that is higher than the gate voltage V(G) by thediffusion potential V_(dif) of pn junction as shown in the followingformula.

V _(ON) ≈V(G)+V _(dif)  (2)

Consequently, by setting the voltage applied to the anode to a levelhigher than this turn-on voltage V_(ON), the light-emitting thyristormay be turned on.

In the state where the light-emitting thyristor T₀ is turned on, thenext transfer clock φ₁ is raised to a high level. Although this transferclock φ₁ is applied to the light-emitting thyristors T₊₁ and T⁻²simultaneously, only the light-emitting thyristor T₊₁ can be turned onby setting the high-level voltage V_(H) of the transfer clock φ₁ to thefollowing range.

V(G ⁻²)+V _(dif) >V _(H) >V(G ₊₁)+V _(dif)  (3)

By doing this, the light-emitting thyristors T₀ and T₊₁ are turned onsimultaneously. When the transfer clock φ₃ is lowered to a low level,the light-emitting thyristors T₀ is turned off, and this completestransferring ON state from the thyristor T₀ to the thyristor T₊₁.

Based on the principle described above, the ON state of thelight-emitting thyristor is sequentially transferred by setting thehigh-level voltage of the transfer clocks φ₁, φ₂ and φ₃ in such a manneras to overlap sequentially and slightly with each other. In this way,the self-scanning light-emitting array according to the presentinvention is accomplished.

FIG. 7 shows an equivalent circuit diagram of a second fundamentalstructure of the self-scanning light-emitting element array. Thisself-scanning light-emitting element array uses a diode as means forelectrically connecting the gate electrodes of light-emitting thyristorsto each other. That is, the diodes . . . D⁻², D⁻¹, D₀, D₊₁ . . . areused in replace of the interactive resistors R_(I) in FIG. 6. The numberof transfer clock lines may be only two due to the unidirectional ofdiode characteristics, then each of two clock (φ₁, φ₂) lines isconnected to the anode electrode of each light-emitting element atintervals of two elements.

The operation of this self-scanning light-emitting element array willnow be described. Assume that as the transfer clock φ₂ is raised to ahigh level, the light-emitting thyristor T₀ is turned on. At this time,the voltage of the gate electrode G₀ is reduced to a level near zerovolts due to the characteristic of the thyristor. Assuming that thesupply voltage V_(GK) is 5 volts, the gate voltage of eachlight-emitting thyristor is determined by the network consisting of theload resistors R_(L) and the diodes D. The gate voltage of an thyristornearest to the light-emitting thyristor T₀ drops most, and the gatevoltages of those thyristors rise as they are further away from thelight-emitting thyristor T₀.

The voltage reducing effect works only in the rightward direction fromthe light-emitting thyristor T₀ due to the unidirectionality andasymmetry of diode characteristics. That is, the gate electrode G₊₁ isset at a higher voltage with respect to the gate electrode G₀ by aforward rise voltage V_(dif) of the diode, while the gate electrode G₊₂is set at a higher voltage with respect to the gate electrode G₊₁ by aforward rise voltage V_(dif) of the diode. On the other hand, currentdoes not flow in the diode D⁻¹ on the left side of the light-emittingthyristor T₀ because the diode D⁻¹ is reverse-viased. As a result, thegate electrode G⁻¹ is at the same potential as the supply voltageV_(GK).

Although the next transfer clock φ₁ is applied to the nearestlight-emitting thyristor T₊₁, T⁻¹; T₊₃, T⁻³; and so on, the thyristorhaving the lowest turn-on voltage among them is T₊₁, whose turn-onvoltage is approximately the gate voltage of G₊₁+V_(dif), about twice ashigh as V_(dif). The thyristor having the second lowest turn-on voltageis T₊₃, about four times as high as V_(dif). The turn-on voltage of thethyristors T⁻¹ and T⁻³ is about V_(GK)+V_(dif).

It follows from the above discussion that by setting the high-levelvoltage of the transfer clock φ₁ to a level about twice to four times ashigh as V_(dif), only the light-emitting thyristor T₊₁ can be turned-onto perform a transfer operation.

FIG. 8 shows an equivalent circuit diagram of a third fundamentalstructure of the self-scanning light-emitting element array. Accordingto the structure, a transfer portion 40 and a light-emitting portion 42are separated. The circuit structure of the transfer portion 40 is thesame as that shown in FIG. 7, and the light-emitting thyristors . . .T⁻¹, T₀, T₊₁, T₊₂ . . . are used as transfer elements in thisembodiment.

The light-emitting portion 42 comprises writable light-emitting elementsL⁻¹, L₀, L₊₁, L₊₂ . . . , each gate thereof is connected to the gate . .. G⁻¹, G₀, G₊₁ . . . of the transfer elements . . . T⁻¹, T₀, T₊₁, T₊₂,respectively. A write signal S_(in) is applied to all of the anode ofthe writable light-emitting elements.

In the following, the operation of this self-scanning light-emittingarray will be described. Assuming that the transfer element T₀ is in theON state, the voltage of the gate electrode G₀ lowers below the supplyvoltage V_(GK) and to almost zero volts. Consequently, if the voltage ofthe write signal S_(in) is higher than the diffusion potential (about 1volt) of the pn junction, the light-emitting element L₀ can be turnedinto a light-emission state.

On the other hand, the voltage of the gate electrode G⁻¹ is about 5volts, and the voltage of the gate electrode G₊₁ is about 1 volt.Consequently, the write voltage of the light-emitting element L⁻¹ isabout 6 volts, and the write voltage of the light-emitting element L₊₁is about 2 volts. It follows from this that the voltage of the writesignal which can write only in the light-emitting element L₀ is a rangeof about 1-2 volts. When the light-emitting element L₀ is turned on,that is, in the light-emitting state, the voltage of the write signalS_(in) is fixed to about 1 volt. Thus, an error of selecting otherlight-elements can be prevented.

Light emission intensity is determined by the amount of current fed tothe write signal S_(in), an image can be written at any desiredintensity. In order to transfer the light-emitting state to the nextelement, it is necessary to first turn off the element that is emittinglight by temporarily reducing the voltage of the write signal S_(in)down to zero volts.

Industrial Applicability

This invention makes it possible to provide an end face light-emittingthyristor having good external light emission efficiency. Aself-scanning light-emitting element array using this end facelight-emitting thyristor has improved external light emission efficiencyand require no driving circuit, thus achieving a low-cost optical printhead for optical printers. When the self-scanning light-emitting elementarray using this end face light-emitting thyristor is applied to opticalprint heads, high-quality printing can be accomplished because eachlight-emitting element has improved external light emission efficiency.

What is claimed is:
 1. An end face light-emitting thyristor for emittinglight from an end face thereof, comprising: a first semiconductor layerof a first conductivity type, a second semiconductor layer of a secondconductivity type, a third semiconductor layer of the first conductivitytype, and a fourth semiconductor layer of the second conductivity typestacked in that order on a substrate of the first conductivity type,wherein the end face includes an edge of at least two of the stackedsemiconductor layers, a first electrode provided on the fourthsemiconductor layer in the vicinity of the edge for injecting currentinto the stacked semiconductor layers, wherein the current injected fromthe first electrode is concentrated near the end face, whereby light isprimarily emitted from the end face, and a second electrode provided onthe third semiconductor layer, wherein the first, second and thirdsemiconductor layers have a necked portion between a region includingthe first electrode and a region including the second electrode.
 2. Aself-scanning light-emitting element array, comprising: a self-scanningtransfer element array having such a structure that a plurality oftransfer elements each having a control electrode for controllingthreshold voltage or current for transfer operation are arranged, thecontrol electrodes of the transfer elements are connected to the controlelectrode of at least one transfer element located in the vicinitythereof via an interactive resistor, power-supply lines are connected tothe transfer elements by electrical means, and clock lines are connectedto the transfer elements, and a light-emitting element array having sucha structure that a plurality flight-emitting elements each having acontrol electrode for controlling threshold voltage or current arearranged, the control electrodes of the light-emitting element array areconnected to the control electrodes of said transfer elements byelectrical means, and lines for applying current for light emission ofthe light-emitting element are provided, wherein the light-emittingelement is an end face light-emitting thyristor as set forth in claim 1.3. A self-scanning light-emitting array, comprising: a self-scanningtransfer element array having such a structure that a plurality oftransfer elements each having a control electrode for controllingthreshold voltage or current for transfer operation are arranged, thecontrol electrodes of the transfer elements are connected to the controlelectrode of at least one transfer element located in the vicinitythereof via an electrically unidirectional element, power-supply linesare connected to the transfer elements by electrical means, and clocklines are connected to the transfer elements, and a light-emittingelement array having such a structure that a plurality of light-emittingelements each having a control electrode for controlling thresholdvoltage or current are arranged, the control electrodes of thelight-emitting element array are connected to the control electrodes ofsaid transfer elements by electrical means, and lines for applyingcurrent for light emission of the light-emitting element are provided,wherein the light-emitting element is an end face light-emittingthyristor as set forth in claim
 1. 4. A self-scanning light-emittingarray of claim 3, wherein the electrically unidirectional element is adiode.